The document discusses centrifugal pumps. It begins by defining a centrifugal pump and explaining its basic working mechanism. It then describes the steps involved in its operation, including priming. Advantages include simple construction and ability to handle solids. Disadvantages are inability to handle highly viscous fluids or operate at high heads efficiently.

1. CENTRIFUGAL PUMP
MAJOR
ASSIGNMENT
SUBMITTED By:
BRIJESH KUMAR
UID-K10668
BRANCH – MECHANICAL(6-
SEM)
SUBMITTED TO :
MR.ADITYA MISRA

2. WHAT IS CENTRIFUGAL PUMP?
WORKING MECHANISM OF A
CENTRIFUGAL PUMP
ADVANTEGAES AND
DISADVANTAGES OF
CENTRIFUGAL PUMPS

3. Centrifugal pump works on the principle that
when a certain mass of liquid is made to rotate
along the impeller from the central axis of rotation,
it impresses a centrifugal head. It causes the water
to move radially outwards at higher velocity and
causes the water to rise to a higher level. The
motion of water is restricted by casing of pump, it
result into pressure build up. In addition , the
change in angular momentum of liquid during its
fiow reults into increase in pressure head.
The steps involved in operation of centrifugal
pump are as follows :
1.The delivery valve is closed.
2.The priming of the pump is carried out. Priming
involves the filling the liquid in suction pipe and
casing upto the level of delivery valve so that no air
pockets are left in the system.
if any air or gas pockets are left in this portion of
pump, it may result into no delivery of liquid by
the pump.

4. 3. The pump shaft and impeller is now rotated
with the help of an external source of power
like a motor or any other prime mover.
The rotation of impeller inside a casing full
of liquid produces a forced vortex which is
responsible in imparting the centrifugal head
to the liquid. It creates a vaccum at the eye of
impeller and causes liquid to rise into suction
pipe from the sump.
4. The speed of impeller should be sufficient to
produce the centrifugal head such that it can
initiate discharge from delivery pipe.
5. Now the delivery valve is opened and the
liquid is lifted and discharge through the
delivery pipe due to its high pressure.
Thus the liquid is continously sucked from
the sump to impeller eye and it is delivered
from the casing of pump through the delivery
pipe.
6. Before stopping the pump, it is necessary to
close the delivery pipe otherwise the back
flow of liquid may take place from the high
head reservoir.

5. :- In case the priming of pump is not
done and the pump is not done and the
pump is not under the operation, the
water present in the pump and suction
pipe will flow back to the sump. The space
occupied by water will be filled by air.
:- The operation of filling the casing ,
impeller and suction pipe and the
portion of delivery pump upto delivery
valve is called priming.

6. :- If the pump is now started, the air
pockets inside the impeller may give
rise to vortices and cause the
discontinuity of flow. Under these
condition, the flow of fluid does not
commence and the pump runs dry. It
causes the rubbing and seizing of the
wearing rings, increases noise level and
vibrations and finally may cause the
serious damage to pump.
:- The priming in resiprocating
pumps is not required since the
pumping is done by positively moving
the fluid out of the cylinder by the
piston. Hence, the air will be displaced
from the casing when the pump starts
and it will get a suction pressure which
will draw the fluid from the sump.

7. Priming for small pumps is done
by hand
:- A foot valve is essential at the
bottom of suction pipe
:- A funnel or priming cup is
provided to fill the water by hand.
An air vent is provided in the
casing of pump. When the water
is filled, the air escapes through
the air vent. It is closed once the
priming is completed

8. Convert the mechanical
energy into hydraulic
energy by centrifugal
force on the liquid
Constitute the most
common type of
pumping machinery
Used to move liquids
through a piping system
Has two main
components:
1. Stationary componets,
casing, casing cover and
bearings
2. Rotating components,
impeller and shaft
Classified into three
categories ; Radial Flow,
Mixed Flow, Axial Flow

9. Simplest piece of
equipment in any process
plant
Energy changes occur by
virtue of impeller and
volute
Liquid is fed into the
pump at the center of a
rotating impeller and
thrown outward by
centrifugal force
The conversion of kinetic
energy into pressure
energy supplies the
pressure difference
between the suction side
and delivery side of the
pump
Liquid flow path
inside a
centrifugal pump

10. •The power supplied to the pump:
Where m=mass flow rate, kg/s
∆H= total discharge head,
N.m/kg
η=efficiency
…………(1)

11. •The power delivered to the fluid:
…………(2)
•From equations (1) and (2)
efficiency:

12. nq is the specific speed for a unit
machine that is geometric similar to a
machine with the head Hq = 1 m and
flow rate Q = 1 m3
/s
43q
H
Q
nn ⋅=
qs nn ⋅= 55,51

13. Three basic
components:
Volute, casing,
body
or Diffuser
Impeller
or impellers
Driver (motor)

14. Centrifugal Pumps
Vanes
Direction of
rotation

15. Centrifugal Pumps
Single suction impeller

16. Centrifugal Pumps
• Open
• Semi-open
• Closed
- Single suction
- Double suction
• Non-clogging
• Axial flow
• Mixed flow

17. Maximum efficiency lies
in the range:
2000<NS<3000
High head, low capacity
pumps:
500<NS<1000
Low head, large capacity
pumps:
NS>15000

18. Centrifugal Pumps
Rotation
Impeller
Blades
Vt
V
r
V
s
Vr = Radial Velocity
Vt = Tangential Velocity
Vs = Vector Sum Velocity

19. Centrifugal Pumps
Suction Eye
Cutwater
Arrows represent the
direction of water flow
Discharge
Nozzle

20. Advantages
Simple in construction
and cheap
Handle liquid with large
amounts of solids
No metal to metal fits
No valves involved in
pump operation
Maintenance costs are
lower

21. Disadvantages
Cannot handle highly viscous
fluids efficiently
Cannot be operated at high
heads
Maximum efficiency holds
over a narrow range of
conditions